This is actually a pretty good question. The condition on the Pokemon Power was put into effect for at least two cards presently in print. The first of which is Muk, which will turn off all Pokemon Powers, and the other is Goop Gas Attack, which turns them off for a turn. While one of these cards are in effect, Snorlax CAN become poisoned, paralyzed, etc.. and the effect would stick when the card no longer had an effect.
Scott